Bus duct



2 sheets-sheet 1 mmmvw@ wh um m Q INVENTOR.

hilf *La H. l. STANBACK June l5, l1965 BUS DUCT Filed April 2, 1963 June15,l 1965 H. l. sTANBAcK BUS DUCT 2 Sheets-Sheet 2 INVENTOR bmfj @WL65m,

mmunHllllllHHm" K- United States Patent O 3,189,680 BUS DUCT Harris I.Stanback, Lexington, Ky., assigner to Square D Company, Park Ridge,lll., a corporation of Michigan Filed Apr. 2, 1963, Ser. No. 269,971Claims. (Cl. 17d-38) This invention relates generally to bus duct, andmore particularly to a joint for separate bus duct sections.

An object of the invention is to provide an improved bus duct joint.

A further object is to provide an improved con-struction for theopposite end portions of the bus bars of a section or length of bus ductto facilitate the serial connection of like bus duct sections.

Other objects and advantages will become apparent when the followingspecication is considered along with the accompanying drawings in which:

FIG. l is a perspective view of a bus duct joint constructed inaccordance with this invention;

FlG 2 is a longitudinal sectional view taken substantially along theline 2 2 of FIG, 1;

FIG. 3 is a cross sectional View of the bus duct joint of FIG. l takensubstantially along the line 3-3 of FIG. 2;

FIG. 4 is a perspective view of an end portion of an inner bus barincluded in the bus duct joint of FlG. l;

FIG. 5 is a sectional View taken substantially along the line 5 5 ofFlG. 4;

FIG. 6 is a perspective view of an end portion of a bus bar assemblyincluded in the bus duct joint of FlG. l; and

FG. 7 is a perspective View of an end portion of another bus barassembly included in the bus duct joint of FIG. 1.

FlGS. l and 2 show a rst end portion l@ of a standard length or sectionof bus duct constructed in accordance with this invention, the endportion 1t) being serially connected to and forming a bus duct jointwith a mating second end portion 12 of another standard bus duct sectionalso constructed in accordance with the invention. By standard length orsection is meant a section of bus duct of a length as normally furnishedby the manufacturer, for example, ten feet. Thus it will be understoodthat the end portion ld is part of a bus duct section which may extendseveral feet leftward from the joint in FIGS. l and 2 and have a leftend portion (not shown) corresponding to the end portion 12, and thatthe end portion 12 is part of a bus duct section which may extendseveral feet rightward from the joint in FiGS. l and 2 and have a rightend portion (not shown) corresponding to the end portion ld.

The bus duct joint formed by the end portions lil and 12 is providedwith a pair of upper and lower cover channels id and l5 having oppositeend portions secured respectively to a pair of upper housing channelslrz and 12a and a pair of lower housing channels liib and 12b of the endportions it) and l2. Further, the end portion 1) is provided with a pairof metal joint covers i7 and 1S which telescope over a pair of metaljoint covers 2l and 22 provided on the end portion 12.

The end portion iti includes the right end portions (FIG. 2) of threebus bars 24, 25, and 2d, of substantially equal thickness, and the endportion 12 includes the left end portions of three bus bars 28, 29, and3l?, of substantially equal thickness, it being understood that theunshown left end portions of the bus bars 24, 25, and 26 arerespectively identical to the left end portions of the bus bars 28, 29,and 3i) shown, and that the unshown right end portions of the bus bars28, 29, and Sti are respectively identical to the right end portions ofthe bus bars 24, 2S, and 26 shown. Thus, the bus bars 2id, 26,

23, and 3l) may be identical to each other, the bus bars 24 and 25 beingdisposed symmetrically to each other in the bus duct section having theend portion l0, and the bus bars 28 and 3d being disposed symmetricallyto each other in the bus duct section having the end portion 12.Further, the bus bar 25 may be identical to the bus bar 29.

The bus bars 2d, 2S, and 26 interleave with the bus bars 28, 29, and 3has shown in FIGS. 2 and 3. For this purpose, the right end portions(FIG. 2) of the bus bars 24 and 26 are outwardly offset a predeterminedamount, and the left end portions of the bus bars 28 and 3@ are offsetan amount greater than the predetermined amount of offset of the bars 2dand 26 by the thickness of one of the bus bars. Further, the left endportion of the bus bar 29 is straight and the right end portion of thebus bar 25 is split longitudinally of the bus bar across the smallercross sectional dimension thereof substantially centrally of the greatercross sectional dimension thereof, the split ends 25a and 25!) beingotfset in opposite directions by the thickness of one of the bus bars.

The right end portion of the bus bar 25 is shown separately in FlGS. 4and 5. An aperture is provided through the right end portion of the busbar 2S', the aperture including a downwardly facing recess 2SC in thelower edge of the split end 25:1 and an upwardly facing recess 25d inthe upper edge of the split end 25h.

The left end portions of the bus bars 2S, 29, and 3i) are providedrespectively with slots 23a, 2%, and Sila opening to the ends of the busbars, as shown in FIG. 7, for transversely receiving a bolt 32 carriedby the end portion l0. Thus, the bus bars of the two end portions liland l2 may be interleaved without removal of the bolt 32 from the endportion ld.

The joint covers 2l and 22 of the end portion l2 become the inner jointcovers of the bus duct joint when the bus duct sections having the endportions lil and l2 are serially connected. The joint covers 2li and 22are provided respectively with` sheets of insulation 35 and 36 securedto the inner surfaces thereof in any suitable manner as by rivets (notshown). An additional pair of insulators 3-7 and 33 in the end portioni2 are trapped respectively between the insulation sheet 35 and the busbar 2S and between the insulation sheet 35 and the bus bar 3d, theinsulators 37 and 3S being provided with raised bosses 39 (FIG. 2)received respectively in holes d@ (FG. 7) provided in the bus bars 255and Si?. lt will be understood that the inner joint covers 2l and 22,the insulation sheets 3d and 36, and the insulators 37 and 3S areprovided with slots generally corresponding with the slots 28a, 29a, and36a in the bus bars 2S, 29, and Stb.

in the end portion lil, a pair of insulating phase barriers 43 and d4are provided respectively between the bus bar 24 and the split end 25hof the bus bar 25 and between the bus bar 26 and the split end 25a ofthe bus bar 25, the barriers d3 and fili being provided with raisedbosses 4S (FiG. 2) received respectively in holes iti (FIG. 6) providedin the bus bars 24 and 2o. Preferably the barriers i3 and de are tightlysecured respectively to the bus bars and 2d by screws, such as a screwi7 (FlGS. 2 and 6), threaded into the barriers d3 and 4d and countersunkin the bus bars 24 and 26.

After the end portions l@ and l2 are assembled, the joint may betightened by turning of the boit 32 which is threaded into an elongatednut d@ and provided with an insulating sheath Good electrical contactmay thus be established respectively between the bus bar 24 of the endportion id and the bus bar 28 of the end portion l2, between the splitends 25a and 25h of the bus bar 2S of the end portion l0 and the bus bar29 of the end portion l2, and between the bus bar 26 of the end portionl@ and the bus bar 3@ of the end portion l2. The joint tightness may bemaintained, despite repeated expansion and contraction of the parts, bya pair of spring washers 5l held captive on the outer suriiaces of thejoint covers 17 and ll@ of the end portion l@ by a plurality ofbent-over tabs 52 sheared from the joint covers. 'l`he nut i9 is heldcaptive in a nut holder 5d secured to the outer surface of the jointcover llti by a pair of bent-over tabs 5e' sheared from the joint coverand a screw Se threaded into a flange of the nut holder through one ofthe tabs 55.

The outer bus bars Zd and 26 of the end portion l@ are respectivelyprovided with a pai-r of slots 5S (FlG. 6) for receiving the bolt 32which also extends through the recesses C an-d 25d in the split ends 25aand 25h of the bus bar 25 and through appropriate holes in the jointcovers 17 and llt, the spring washers Sll and the phase barriers 43 andLid. rThe same die used to form the holes and the slots 23a, 29a, andSila in the bus bars 2S, 23, and 3@ may be used to form the holes de andslots 5S in the bus bars 24 and 26.

rThe phase barrier-s 413 and 4d are identical but inverted with respectto each other, a raised or thickened portion 43a (FllG. 3) on thebarrier d3 filling the space above the split end Zb ot the bus bar Z5,and a raised or thickened porti-on 44a on the barrier 4dtilling thespace below the split end 25a of the bus bar 25.

It will be seen that an improved bus duct structure has tbe/en providedwhich penmits easy connection of like bus duct sections and that asingle bolt with a captive nut and spring washers may be tightened toestablish good electrical connections between the respective bus bars ofthe Separate bus duct sections. Further, large areas of mechanicalcontact are also provided between the various insulators, bus bars, andjoint covers Ifor good heat dissipating ability at the joint.

Various modiiioations may be made in the structure disclosed withoutdeparting from the spirit and scope oi the invention.

I claim:

l. A ibus bar assembly comprising an inner flat elongated bus bar havingan end portion split longitudinally of the bus bar across the smallercross sectional dimension thereof to form two separate end pontions,said two Iseparate end portions being off-set in opposite directionsparallel to said smaller cross sectional dimension to deiine -a spacetherebetween of a width substantially equal to the thickness of the busbar, and a pair of outer iiat elongated bus bars disposed on oppositesides of said inner bus bar in relatively closely spaced fiatwiserelationship thereto, each of said outer bus bars having a pair oflongitudinally opposite firs-t and second end portions, the first endportion being outwardly oiset a predetermined amount and the second endportion being outwardly otset an amount greater than said predeterminedamount of offset of said rst end .portion by an amount substantiallyequal to the thickness of the bus bar.

2. A bus duct joint comprising a pair of separate serially connectedlengths of bus duct, each of said lengths of bus duct having three datelongated relatively closely spaced bus bars disposed in atwise stackedrelationship to each other, all six of the bus bars being ofsubstantially the same thickness, the center bus bar of one of saidlengths of bus duct having an end portion which is adjacent the other ofsaid lengths of bus duct and is split longitudinally of the bus baracross the smaller cross sectional dimension thereof to form twoseparate end p01'- tions, said two separate end portions being ofset inopposite directions parallel to said smaller cross sectional dimensionlto dene a space therebetween of a width substantially equal to thethickness of one of said bus bars, the center bus bar of said other ofsaid lengths of bus duct having an end portion which is adjacent saidone of said lengths of bus duct and is str-aight and is electricallyconnected to and received in said space between said two separateoppositely oiset end portions of said split end portion of said centerbus .bar of said one of said lengths of bus duct, the two outer bus barsof each of said lengths of bus duct having equally, oppositely andoutwardly offset end portions adjacent the other of said lengths of busduct, and said end portions of the two outer bus bars of one of saidlengths of bus duct being respectively offset more than said endportions of the two outer bus bars of the other of said lengths oi' busduct by an amount substantially equal to the thickness of one of saidbus bars and being respectively electrically connected thereto andinterleaved therewith. Y

3. Abus duct joint as claimed in claim 2, wherein the interleaved endportions of the bus bars of said connected lengths of bus duct have asingle bolt extending, said bolt being mounted in the end portions ofthe three bus bars of one of said lengths of bus duct, and the endportions of the three bus bars of the other of said lengths of bus ductare provided with open-ended slots extending longitudinally of the busbars, said bolt being received in said slots, whereby the bus bars ofthe two lengths of bus duct may be interleaved without removal of saidbolt trom said one of said lengths of bus duct.

' d. A bus duct joint as claimed in claim 3, wherein said bolt isprovided with an elongated nut held captive and prevented from rotatingby a nut holder secured to said one of said lengths ot bus duct.

5. A bus duct joint as claimed in claim 2, wherein a pair `of 4phasebarriers are provided respectively adjacent the outer surfaces of thetwo separate oppositely offset end portions formed by said split in thecenter bus bar of said one of said lengths of bus duct and the phasebarriers are respectively provided with raised portions edgewise`aligned with said separate end portions formed by said split and havinga thickness substantially equal to the thickness of one of said busbars.

References ited by the Examiner Y UNITED STATES PATENTS 3,115,379 12/63McKee 339-47 lOl-IN F. BURNS, Primary Examiner. JOHN P. WLDMAN, E. EAMESSAX, Examiners.

EIL

1. A BUS BAR ASSEMBLY COMPRISING AN INNER FLAT ELONGATED BUS BAR HAVINGAN END PORTION SPLIT LONGITUDINALLY OF THE BUS BAR ACROSS THE SMALLERCROSS SECTIONAL DIMENSION THEREOF TO FORM TWO SEPARATE END PORTIONS,SAID TWO SEPARATE END PORTIONS BEING OFFSET IN OPPOSITE DIRECTIONSPARALLEL TO SAID SMALLER CROSS SECTIONAL DIMENSION TO DEFINE A SPACETHEREBETWEEN OF A WIDTH SUBSTANTIALLY EQUAL TO THE THICKNESS OF THE BUSBAR, AND A PAIR OF OUTER FLAT ELONGATED BUS BARS DISPOSED ON OPPOSITESIDES OF SAID INNER BUS BAR IN RELATIVELY CLOSELY SPACED FLATWISERELATIONSHIP THERETO, EACH OF SAID OUTER BUS BARS HAVING A PAIR OFLONGITUDINALLY OPPOSITE FIRST AND SECOND END PORTIONS, THE FIRST ENDPORTION BEING OUTWARDLY OFFSET A PREDETERMINED AMOUNT AND THE SECOND ENDPORTION BEING OUTWARDLY OFFSET AN AMOUNT GREATER THAN SAID PREDETERMINEDAMOUNT OF OFFSET OF SAID FIRST END PORTION BY AN AMOUNT SUBSTANTIALLYEQUAL TO THE THICKNESS OF THE BUS BAR.